Abstract: [Objective] In this paper, the quantity characteristics of two typical epiphytic ferns, Neottopteris nidus and Pseudodrynaria coronans,were investigated to provide basic information for evaluating the characteristics of the two ferns and monitoring the biodiversity located in canopy.[Method] The primary forests (PFs) and degraded primary forests (DPFs) were analyzed respectively using data from 16 plots, at which all the two nest ferns can be present. The two types of communities were compared of their elevation of distribution, size and density, and density of hosts, number of nest ferns on individual hosts. The Shapiro-Wilk method or distribution models of those measurements were fitted. The diffusion coefficient (C) was calculated to decide hosts' distribution pattern.[Result] Average density of the two nest ferns in PFs was 111.2 individual·hm^-2, and in DPFs was 210.6 individual·hm^-2. Average density of hosts in PFs and DPFs were 72.8 and 117.8 individual·hm^-2, respectively. The sum of host species was 79 species which belong to 53 genera of 31 families. All the hosts are tree species except Tetrastigma planicaule, a vine of N. nidus could only be found on 25 host species and P. coronans was only present on 17 host species. There were 24 host species could only be found in PFs and 48 in DPFs. And 7 host species (i.e. common host species) could be found in both types of plots. The height of the two nest ferns were in the range of 0.525.0 m, but 69.5% of them lower than 10 m and 39.7% of them in a height range of 5.09.0 m. Ferns size, ferns density, hosts density, and ferns on per host could be described well by negative exponential function. Hosts in PFs and DPFs were clumped distribution patterns.[Conclusion] In rain forests of the study region, the two nest epiphytic ferns tended to fasten on hosts in a height range of 5.09.0 m although they could be found in height range of 0.525.0 m, and they were in clumped distribution patterns in the horizontal direction. It was interesting that ferns size and density, hosts density and ferns on per host appeared an inverse "J" pattern together. To explore the reason why more of the two nest epiphytic ferns were present in DPFs than in PFs, it was recommended that the relations of their richness and abundance with forest community type, structure and microclimate should be analyzed next step.

Key words: mountain rain forest, nest epiphytic ferns, hosts, distribution pattern, height, size, density